c_poly.r

## wtf
#' Combine a list of PolygonDataFrame objects into a single object. 
#' 
#' Objects are combined by modifying sequential IDs to increase. 
c_poly <- function(x) {
  poly <- x[[1]]
  if (length(x) == 1L) {
    warning("input of length one, returning first element")
    return(poly)
  }
  for (i in seq_along(x)[-1]) {
    x0 <- spChFIDs(x[[i]], as.character(seq(nrow(x[[i]])) + max(as.integer(row.names(poly)))))
    poly <- maptools::spRbind(poly, x0)
  }
  poly
}